10 Mr. W. H. Benson on the Genus Camptoceras. 



Genus Camptoceras, Benson. 

 (Character emendatus et auctus.) 



Testa sinistrorsa, imperforata, elongato-elliptica, spira soluta, apice 

 acutiusculo, sutura late et profunde excavata (re vera omiiino 

 careiite) ; anfractibus 3-4 angustis elongatis, superne et subtus 

 carinatis, lateribus planulatis ; apicali elongato-acuminato, longe 

 exserto ; ultimo antice superne descendente, carinato ; apertura 

 soluta, Integra, magna, spiram non sequante, elongato-elliptica, 

 angustiuscula, superne et ad basin arcuatim angulata ; peristomate 

 acuto ; operculo nuUo. 



Species unica, 



C, Terebra, Benson. 



Testa elongato-elliptica, hyalina, vel albido-cornea, _ 

 lineis spiralibus, exiguis, vix elevatis, striis ob- 

 liquis confertissime decussatis ; apertura verti- J^ 

 cali, elliptica; peristomate acuto, vix expansi- 

 usculo. 



Long, vix 9, plerumque 6 ad 7 mill. 



Diam. 3 mill. Long, apert. exempl. majoris 4 mill. 



C. Terebra. 



Syn. C. Terebra, Benson, Calcutta Journ. Nat. Hist. 1842. 

 Mab. in lacu paludoso prope Moradabad, agro Roliillano. 



AnimaL 



Animal tentaculis duobus filiformibus, obtusis, oculis magnis inter 

 tentacula sitis, proboscideque mediocri munitum ; pallio labia testae 

 baud transeunte ; pede brevi, longitudinem aperturse vix superante. 



The form of the tentacula and the position of the eyes, situated 

 between the filiform tentacula, and sessile on the head (not, as 

 in Li/mmea, occupying the fore part of the widened base of the 

 triangular tentacula), at once distinguish the animal from that of 

 Lymncea. In Camptoceras the eyes are large in proportion to 

 the size of the animal, while in Lymncea they present only a 

 minute black point, even in individuals of large size. In Ancylus 

 also the eyes are small, and inserted in two lateral lobes pro- 

 ceeding from the tentacular laminae, which are triangular and 

 truncated*. The shortness of the foot, however, the sluggish 

 movements of the moUusk, and its strong adhesion to smooth 

 surfaces, point to an affinity with Ancylus, which, instead of 

 presenting the elongate, imperfectly rolled, acutely spiral cone 



* Vide Dupuy, MoUusques de France. 



